In order to know what size wind turbine you should use you need to calculate the average wind speed where you live.
Step 1 - How Much Average Wind Speed Do You Need
You must have over 10 miles per hour (mph) to generate enough energy to produce electricity.
Step 2 - Using an Anemometer
A basic aneometer is a weather instrument that measures the average wind speed. More sophisticated aneometer measures wind speed, direction and pressure.
Step 3 - How an Anemometer Works
The most common type of aneometer is the spinning cup. Mounted on a vertical pole three or four cups are set at a 45 degree angle. A magnet is attached to one of the cups. Blowing wind is caught in the cups forcing the aneometer to spin on the pole. When the aneometer makes a full rotation the cup with the magnet is detected by a reed switch. This triggers an output pulse equal to the average wind speed.
Step 4 - Calculating the Average Wind Speed
By counting the number of pulses over time they are converted into an average wind speed. The wind speed is logged and after a year of observation the numbers are averaged to find the wind speed in your area. In order, to gain an accurate average wind speed the aneometer should be used and data recorded for at least three years.
Step 5 - Finding the Average Wind Speed Without Using an Aneometer
There are sites available on the Internet to find the average wind speed across the country. However the data on the Internet is not as accurate as calculating the average wind speed yourself.